2017-05-31

The classic definition of the microservice architectural style “as an approach to developing a single application as a suite of small services, each running in its own process and communicating with lightweight mechanism” creates a lot of fears and misunderstandings:

Application monoliths are evils, but having too many microservices sounds like creating an (unknown) evil as well.

Everything has to be re-developed.

Microservices will create a huge backlog for our agile team.

Microservices? They are neither architecture nor architectural style – just a technical stack.

As usual in IT, any new technology or methodology (which pretends to revolutionized everything) must be used together with many existing ones. Let us “intermix” MSA with some existing and proven technologies and methodologies.

MicroService Architecture (MSA) bring two major concepts:

microservice as a unit-of-functionality, unit-of-deployment and unit-of execution with the same boundaries, and

Using these two concepts, let us try to find a practical balance between monolith architecture and MSA.

Firstly, it is necessary to think about any application as a set of the following artefacts

Events

Roles (actually, access rights management)

Rules (or decisions)

Business objects – data structures

Business objects – documents

Human activities (or screens or interactive services)

Automation activities (or scripting fragments or automation services)

Coordination

Audit trails

KPIs

Reports

Secondly, consider that each artefact must be, ideally, handled

Explicitly

As a set of microservices

Via APIs

With versioning

By a specialized OTS tool, e.g. data structures are handled by a database, processes are handled by a BPM-suite tool

In a Domain Specific Language (DSL), e.g. BPMN for processes, DMN for rules

Over its whole life cycle

Thirdly, understand specialised tools for that each artefacts:

Coordination as explicit and machine-executable processes via a BPM-suite tool

Roles via an access management tool

Documents via an ECM product

Automation fragments as scripts in an interpretive language and execution robots

Audit trail and reports via BI tools

etc.

Fourthly, prepare two common “pool” for future tools, services and microservices:

technological pool for generic off-the-shelf products; their functionality is available via APIs

enabling pool for services, microservices, tools which are a) specific for the particular organisation and b) potentially reusable within organisation; their functionality is available via APIs

For each monolith application, sort its functionality out into 2 common pools and an individual pool.

At the result, we got a corporate unified business execution platform which standardise and simplify core elements of the corporate-wide computing system. For any elements outside the platform, new opportunities should be explored using agile principles. These twin approaches should be mutually reinforcing:

The platform frees up resource to focus on new opportunities while successful agile innovations are rapidly scaled up when incorporated into the platform.

An agile approach requires coordination at a system level.

To minimise duplication of effort in solving the same problems, there needs to be system-wide transparency of agile initiatives.

Existing elements of the platform also need periodic challenge. Transparency, publishing feedback and the results of experiments openly, will help to keep the pressure on the platform for continual improvement as well as short-term cost savings.

2017-05-22

Everyone heard about the DevOps culture which refers to a set of practices that emphasize the collaboration and communication of both software developers and IT professionals while automating the process of software delivery and infrastructure changes.

Certainly, DevOps improves the time-to-market for digital solutions, but it spans only a down-stream part of the idea-to-solution value stream. To cover the whole value stream, any up-stream stumbling blocks must be removed.

An application architecture, which is built on microservices and their machine-executable coordination (e.g. by processes), enables a new BizDevOps culture by quick implementations of business ideas. (I think that ING has introduced the BizDevOps concept).

Microservice is a service with the same boundaries as

a unit-of-functionality (for Biz)

a unit-of-deployment (for Dev)

a unit-of-execution (for Ops)

Thus, an implementation of a business idea as a group of microservices will have no unnatural complexity and, therefore, its time-to-market will be short.